1#### 2# kbuild: Generic definitions 3 4# Convenient constants 5comma := , 6squote := ' 7empty := 8space := $(empty) $(empty) 9 10### 11# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o 12dot-target = $(dir $@).$(notdir $@) 13 14### 15# The temporary file to save gcc -MD generated dependencies must not 16# contain a comma 17depfile = $(subst $(comma),_,$(dot-target).d) 18 19### 20# filename of target with directory and extension stripped 21basetarget = $(basename $(notdir $@)) 22 23### 24# Escape single quote for use in echo statements 25escsq = $(subst $(squote),'\$(squote)',$1) 26 27### 28# filechk is used to check if the content of a generated file is updated. 29# Sample usage: 30# define filechk_sample 31# echo $KERNELRELEASE 32# endef 33# version.h : Makefile 34# $(call filechk,sample) 35# The rule defined shall write to stdout the content of the new file. 36# The existing file will be compared with the new one. 37# - If no file exist it is created 38# - If the content differ the new file is used 39# - If they are equal no change, and no timestamp update 40# - stdin is piped in from the first prerequisite ($<) so one has 41# to specify a valid file as first prerequisite (often the kbuild file) 42define filechk 43 $(Q)set -e; \ 44 echo ' CHK $@'; \ 45 mkdir -p $(dir $@); \ 46 $(filechk_$(1)) < $< > [email protected]; \ 47 if [ -r $@ ] && cmp -s $@ [email protected]; then \ 48 rm -f [email protected]; \ 49 else \ 50 echo ' UPD $@'; \ 51 mv -f [email protected] $@; \ 52 fi 53endef 54 55###### 56# gcc support functions 57# See documentation in Documentation/kbuild/makefiles.txt 58 59# checker-shell 60# Usage: option = $(call checker-shell,$(CC)...-o $$OUT,option-ok,otherwise) 61# Exit code chooses option. $$OUT is safe location for needless output. 62define checker-shell 63 $(strip 64 $(shell set -e; \ 65 DIR=$(KBUILD_EXTMOD); \ 66 cd $${DIR:-$(objtree)}; \ 67 OUT=$$PWD/.$$$$.null; \ 68 if $(1) >/dev/null 2>&1; \ 69 then echo "$(2)"; \ 70 else echo "$(3)"; \ 71 fi; \ 72 rm -f $$OUT)) 73endef 74 75# as-option 76# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,) 77as-option = $(call checker-shell,\ 78 $(CC) $(CFLAGS) $(1) -c -xassembler /dev/null -o $$OUT,$(1),$(2)) 79 80# as-instr 81# Usage: cflags-y += $(call as-instr,instr,option1,option2) 82as-instr = $(call checker-shell,\ 83 printf "$(1)" | $(CC) $(AFLAGS) -c -xassembler -o $$OUT -,$(2),$(3)) 84 85# cc-option 86# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586) 87cc-option = $(call checker-shell,\ 88 $(CC) $(CFLAGS) $(if $(3),$(3),$(1)) -S -xc /dev/null -o $$OUT,$(1),$(2)) 89 90# cc-option-yn 91# Usage: flag := $(call cc-option-yn,-march=winchip-c6) 92cc-option-yn = $(call cc-option,"y","n",$(1)) 93 94# cc-option-align 95# Prefix align with either -falign or -malign 96cc-option-align = $(subst -functions=0,,\ 97 $(call cc-option,-falign-functions=0,-malign-functions=0)) 98 99# cc-version 100# Usage gcc-ver := $(call cc-version,$(CC)) 101cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC)) 102 103# cc-ifversion 104# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1) 105cc-ifversion = $(shell [ $(call cc-version, $(CC)) $(1) $(2) ] && echo $(3)) 106 107# ld-option 108# Usage: ldflags += $(call ld-option, -Wl$(comma)--hash-style=both) 109ld-option = $(call checker-shell,\ 110 $(CC) $(1) -nostdlib -xc /dev/null -o $$OUT,$(1),$(2)) 111 112###### 113 114# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj= 115# Usage: 116# $(Q)$(MAKE) $(build)=dir 117build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj 118 119# Prefix -I with $(srctree) if it is not an absolute path, 120# add original to the end 121addtree = $(if \ 122 $(filter-out -I/%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1))) $(1) 123 124# Find all -I options and call addtree 125flags = $(foreach o,$($(1)),\ 126 $(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o))) 127 128# echo command. 129# Short version is used, if $(quiet) equals `quiet_', otherwise full one. 130echo-cmd = $(if $($(quiet)cmd_$(1)),\ 131 echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';) 132 133# printing commands 134cmd = @$(echo-cmd) $(cmd_$(1)) 135 136# Add $(obj)/ for paths that are not absolute 137objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o))) 138 139### 140# if_changed - execute command if any prerequisite is newer than 141# target, or command line has changed 142# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies 143# including used config symbols 144# if_changed_rule - as if_changed but execute rule instead 145# See Documentation/kbuild/makefiles.txt for more info 146 147ifneq ($(KBUILD_NOCMDDEP),1) 148# Check if both arguments has same arguments. Result is empty string, if equal. 149# User may override this check using make KBUILD_NOCMDDEP=1 150arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \ 151 $(filter-out $(cmd_$@), $(cmd_$(1))) ) 152endif 153 154# >'< substitution is for echo to work, 155# >$< substitution to preserve $ when reloading .cmd file 156# note: when using inline perl scripts [perl -e '...$$t=1;...'] 157# in $(cmd_xxx) double $$ your perl vars 158make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1))))) 159 160# Find any prerequisites that is newer than target or that does not exist. 161# PHONY targets skipped in both cases. 162any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^) 163 164# Execute command if command has changed or prerequisite(s) are updated. 165# 166if_changed = $(if $(strip $(any-prereq) $(arg-check)), \ 167 @set -e; \ 168 $(echo-cmd) $(cmd_$(1)); \ 169 echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd) 170 171# Execute the command and also postprocess generated .d dependencies file. 172# 173if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \ 174 @set -e; \ 175 $(echo-cmd) $(cmd_$(1)); \ 176 scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\ 177 rm -f $(depfile); \ 178 mv -f $(dot-target).tmp $(dot-target).cmd) 179 180# Will check if $(cmd_foo) changed, or any of the prerequisites changed, 181# and if so will execute $(rule_foo). 182# Usage: $(call if_changed_rule,foo) 183# 184if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ), \ 185 @set -e; \ 186 $(rule_$(1))) 187 188### 189# why - tell why a a target got build 190# enabled by make V=2 191# Output (listed in the order they are checked): 192# (1) - due to target is PHONY 193# (2) - due to target missing 194# (3) - due to: file1.h file2.h 195# (4) - due to command line change 196# (5) - due to missing .cmd file 197# (6) - due to target not in $(targets) 198# (1) PHONY targets are always build 199# (2) No target, so we better build it 200# (3) Prerequisite is newer than target 201# (4) The command line stored in the file named dir/.target.cmd 202# differed from actual command line. This happens when compiler 203# options changes 204# (5) No dir/.target.cmd file (used to store command line) 205# (6) No dir/.target.cmd file and target not listed in $(targets) 206# This is a good hint that there is a bug in the kbuild file 207ifeq ($(KBUILD_VERBOSE),2) 208why = \ 209 $(if $(filter $@, $(PHONY)),- due to target is PHONY, \ 210 $(if $(wildcard $@), \ 211 $(if $(strip $(any-prereq)),- due to: $(any-prereq), \ 212 $(if $(arg-check), \ 213 $(if $(cmd_$@),- due to command line change, \ 214 $(if $(filter $@, $(targets)), \ 215 - due to missing .cmd file, \ 216 - due to $(notdir $@) not in $$(targets) \ 217 ) \ 218 ) \ 219 ) \ 220 ), \ 221 - due to target missing \ 222 ) \ 223 ) 224 225echo-why = $(call escsq, $(strip $(why))) 226endif 227